What's New -  February, 2006

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February 28, 2006:   Oscilloscope Version 4 posted today adds a dual trace function using stereo input signals.  Plus,  the visual layout has been improved  to appear more "oscilloscope-like".      Many thanks to "Krille", a  sharp Delphi programmer from Sweden for doing most of the work on these changes. 

February 26, 2006:  We have been neglecting puzzle programs lately, but we'll be correcting that in the coming weeks.   I finally got around to browsing though one of the books I received for Christmas (The Giant Book of Mensa Mind Challenges) and found several good candidates in the first few minutes.  The first  posted today is Added Corners:  "Place the digits 1..8 in the 8 figures so that each square contains the  sum of the numbers in the adjoining circles."

February 19, 2006:  While writing last week's Olympic Rings program, I thought I would have to find the intersection points of the rings in order to complete the illusion of rings passing over and under neighboring rings.   I turns out, I did not need the exact points.  Redrawing 90 degree arcs in the appropriate quadrants was good enough.,  But it did plant the idea for a program investigate the math behind  Circle Intersections which I posted today in our Math_Topics section. 

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February 15, 2006:  Every Olympic year, our Olympic Rings puzzle gets lots of hits.  This year is no exception.  Here's the entire email from a young lady (I'm assuming), who is upset because DFF didn't answer her question:  "You need to show how to draw the rings. I was not satisfied you will never get my service again. i will not say goodbye"  Who could ignore criticism like that?    Here is a posting,  in the Beginners page of Delphi Techniques that shows one way to do it using "ellipse" and "arc" procedures..  

February 10, 2006:  Version 3.2 of our Cutlist program was posted today.  It fixes a few bugs and adds two new worthwhile features:  fractional representation of dimensions for input or display, and the ability to select a subset of the supply pieces to be considered in searching for solutions.  

February 7, 2006:  One of the good suggestions not implemented in the latest update of our Cutlist work layout program was the ability to input dimensions and display results in fractional rather than decimal form.  Users of the English system of measurement typically use plans and have tape measures that specify lengths in 64th of an an inch or some multiple (32nd, 16ths, 8ths, 4ths or 1/2).   I've coded procedures to convert fractional form input strings to internal decimal form and internal floating point numbers to  fractional formatted strings for display.  Version 3 of  Decimal to Fraction demo program, posted today,  served as the test bed for these new procedures. 

February 3, 2006:   I've been looking at some code written by a Croatian Engineering student for the past few days.  (I love the fact that I get to communicate with Delphi users in so many different countries. )  Variable names in Croatian added to the challenge!  Their instructor required the used of dynamically allocated records and pointers in solving the problem and it brought to light  a common memory leak problem - not releasing memory that you specifically allocate.  Failing to do so in a recursively called procedure aggravates the problem with "stack overflow error" as a common symptom.  It led me to write this small Memory Leak Demo program for the Beginner's page in Delphi Techniques section of DFF.   

February 1, 2006:  A new version of of DFF Library file, DFFV05.zip, was posted today.  It includes a minor bug fix to the modulo function in the big integer class, TInteger, in unit UBigIntsV2.  Program BigIntsTest illustrates the change. 

The Mathslib unit is now officially included in DFFLibV05.  MathsLib  contains a number of math related procedures and functions which I've written over the years and collected there when i got tired of searching them out the second time I needed them.  File DFFLibV05.txt  lists the routines included.   A few StringGrid procedures have been added to the DFFUtils unit to  insert,  delete, or sort  rows.  Also added were string functions to sort ascending, descending or rotate string characters and the missing Delphi  function, StrToFloatDef,   to convert a string value to floating point format or return a default value if the string is invalid.